import com.fasterxml.jackson.databind.ObjectMapper;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

class User {
    public String username;
    public String password;
}
@WebServlet("/json")
public class JsonServlet extends HttpServlet {
    //使用Jackson 最核心的对象就是 objectMapper
    private ObjectMapper objectMapper = new ObjectMapper();

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //通过POST 请求的body , 传递过来一个json格式的字符串
        //
        User user = objectMapper.readValue(req.getInputStream(),User.class);
        System.out.println("username=" + user.username + " password=" + user.password);

        resp.getWriter().write("ok");
    }

}
